The magnitude of wind power is proportional to wind speed, height above ground and area of propeller. Therefore, the present commercial wind power generators are horizontal axis wind turbines with generators located on high towers and equipped with wide-span propellers. The recently built wind turbine in China at the Harbor of Hangzhou has a tower height of 150 meters, a propeller with blade spanning 125 meters and a total weight exceeding 400 tons. Furthermore, wind power generation is restrained in seasons, regions and power grid facilities. Off shore wind turbines would cost 20 to 30 times more if they were built on ground. In China, only 70% of wind turbines are utilized while the rest 30% are idled due to insufficient power grids for energy distribution.
Contemporary wind turbines can only work at low altitude where the wind speed is low and inconsistent. They require for the use of expensive high ratio gear boxes to step up revolution prior to coupling to expensive DC generators which are of low speed and large-diameter-rotor design in order to accommodate more winding coils and more sets of permanent magnets for optimal output. A great portion of wind energy would be lost and dissipated in this very early stage. The power generated shall be, first of all, stored in battery banks, then converted to AC power via DC-to-AC inverters, and then further processed by step-up transformers and voltage regulators prior to connection to power grids. The efficiency of wind power, with an assumption of a 10 m/sec wind speed, to AC power output may be as low as 7.2%, while its high loss in power transmission to destination further deteriorates its efficiency, thus rendering high costs for wind power generation. At high altitude, there is always consistent strong wind available for wind power generation around the year. High speed, high efficient, light weight and low cost AC generators would be used if the wind turbines could be sustained at altitude. Hence, airborne wind power generator systems have been the hot topics of research and exploitation in renewable power generation since the past couple decades.
However, existing wind power generator systems are very expensive, difficult to maintain and operate, and cannot provide steady and reliable power output. Hence, there is a strong desire to exploit for other means of wind power generator system that may be lower in costs, easier to maintain and operate, and capable of providing a more steady and reliable power output.
The above description of the background is provided to aid in understanding a wind power generator system, but is not admitted to describe or constitute pertinent prior art to the wind power generator system disclosed in the present application, or consider any cited documents as material to the patentability of the claims of the present application.